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Rorippa columbiae Census on Chiloquin Ranger District
and Klamath Falls Resource Area
Missy Anderson, Fremont-Winema National Forest
December 12, 2014
INTRODUCTION: This report summarizes a portion of the field survey work requested in
submitted proposal “Survey and Conservation Assessment Development for Columbia yellow
cress (Rorippa columbiae).” Partial funding was available to complete some field survey during
the 2014 season.
OBJECTIVE: Revisit six of the known populations on the Lakeview District BLM and
Fremont-Winema NF and determine current status and condition. Census data is available for
several of these sites and will be used to provide an accurate evaluation of population trends at
those sites.
The revisit surveys were conducted on approximately 525 acres of during June-July 2014. See
attached map.
BACKROUND: Columbia yellow cress occurs in three disjunct regions, along the Columbia
River in Washington and Oregon, in southeastern Oregon and on the Modoc Plateau in
California. Although this species has a fairly large range, populations are sparsely distributed and
are confined to the edges of drying rivers, streams or lakes where the low-growing rhizomatous
perennial receives annual inundation for at least part of the year. Many populations contain only
a few individuals. Monitoring in Washington between the 1980’s and 2003 documented a
precipitous decline in populations within Department of Energy’s Hanford Reach on the
Columbia River. Although Oregon populations along Malheur Lake and in the Sprague River
valley were stable through the 1990’s, no current information on trends in these areas is
available. Plant numbers at Lakeview BLM’s Foley Lake ACEC/RNA (Oregon’s largest
population, with over 10,000 plants observed in 1994) have plummeted, with only 89 plants
recorded in 2007, the last year a census was completed. No plants were observed by ODA staff
at Foley Lake in 2009 and 2010. USFS botanists report large declines in populations under their
jurisdiction, although censuses have not been completed on most sites since the early 1990’s.
This species has received relatively little conservation attention in Oregon in the last decade.
Hydrological changes have negatively impacted sites in Washington and insufficient information
on Oregon sites is available to accurately evaluate the current status of the species. There is
consensus among the state and federal agencies that the species is in decline across much of its
range. Accurate documentation of the status of Columbia yellow cress and revision of
information to produce a Conservation Assessment and determination of the need for a revised
Conservation Strategy will promote proactive conservation planning for the species.
TARGET SPECIES LIST AND RANKS:
Rorippa columbiae (Columbia yellow cress) G3, N3, S3, ORBIC List 1,
WA-S1S2, CA-S1.1, Sensitive
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Project Design and Methods: A census of six populations on Fremont-Winema NF and
Lakeview BLM (Klamath Falls Resource Area) was completed by Sarah Malaby under purchase
order to provide preliminary data. Element Occurrence forms were filled out and populations
GPSed.
Results: Six sites and adjacent ground were surveyed, covering about 525 acres.
Table 1. Summary of Rorippa columbiae (ROCO3) Sites
ROCO3 EO
060212EO00100
name of site
year of visit # plants
Seput Land exchange
1993
348
2014
6
060212EO00056
Sprague River
1994
2003
2014
650
1040
2620
KFRA08111983ROCO3-1 BLM Stukel Mtn
2001
2014
144
43
060212EO00082
Buck Creek
1993
1997
2014
24
0
0
060212EO00083
Buck Creek tributary
1994
1999
2003
2014
150
309
54
11
060212EO00085
Rock Creek
1993
1997
2014
2279
2772
246
2,926
Total plants in 2014
In summary there were six sites of Columbia yellow cress surveyed. Five sites are on Chiloquin
Ranger District and one, Stukel Mt., is on Klamath Falls RA. One site, Buck Creek, appears to
be extirpated. A total of 2,926 plants were counted in 2014. The sum using the highest plant
count from each site prior to 2003 equals 4,637 plants.
Discussion: Overall the trend appears to be declining. The number of plants tallied in the 2014
census decreased between 30-100% as compared to 1990’s counts in 5 of the 6 sites. One site,
Sprague River, did show an increased number of plants. Three of the larger sites (Sprague River,
Rock Creek and Buck Creek Tributary) have plant counts from revisits in 1997-2003, which all
show an increase in the number of plants present compared to the original count in 1993 or 1994.
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Plant counts over 20 years show variability in the populations, as would be expected given other
observations of this species. However, the level of decline seems to be the result of more than
variability in population size in response to precipitation amounts or another single
environmental factor. There is also considerable variability in the conditions at each site; see
Table 2, below.
Table 2. Summary of site conditions
Other
Soil
# of
%
Competition
Habitat type
disturbance
moisture
plants change
Intermittent
Yes with
stream with
50-75% cover
Yes - Ciar4, Canu4 substantial soil
No
wet-dry
0
-100%
water
of graminoids
disturbance
present
Buck Creek
Intermittent
Yes, but not
OHV use in
stream
Yes - non-native
50-75% cover
utilized so far
stream
dry
11
-93%
channel - no
grasses
of graminoids
this year
channel
water
Buck Tributary
Yes - Ciar4,
Broad flood
Canu4, Onac,
75-95% cover moist- plain of the
Trpe21, Phar3 and
2,620 +403%
No
No
Sprague
of graminoids
dry
non-native
River
grasses
Sprague River
Riverbank Yes - Ciar4, Lida, Not in the past 2
3-4' above
5-25% cover
Phar3 and non- years, heavy use
No
dry
6
-98%
the Sprague
of graminoids
prior to that
native grasses
River
Seput
Moderate use
In stream
channel
Yes - Ciar4, Canu4 for the past
Insect
5-25% cover moistseveral years,
with water
and non-native
246
-89%
damage of graminoids
dry
heavy use in the
present and
grasses
past
along bank.
Rock Creek
Yes - heavily
Edge of
utilized along
25-50% cover moistseasonal
Not significant
OHV use
14
-30%
edge of
of graminoids
dry
reservoir
reservoir
Stukel 1
Site location
Non-natives
Yes - Ciar4
Stukel 2
Grazing
Yes - substantial
minor OHV 25-50% cover
ground
activity
of forbs
disturbance
dry
Dried
reservoir
bottom
29
-77%
*USDA NRCS PLANTS Database codes: Canu4 = Carduus nutans (nodding plumeless thistle); Ciar4 = Circium
arvense (Canada thistle); Lida = Linaria dalmatica (Dalmatian toadflax); Onac = Onopordum acanthium (Scotch
cottonthistle); Phar3 = Phalaris arundinacea (reed canarygrass); Trpe21 = Tripleurospermum perforatum (scentless
false mayweed)
The Sprague River site was the only site that showed an increase in the number of plants tallied.
This site is probably closest in its current disturbance regime to what historic conditions were:
the site is in a broad floodplain of one of the major rivers in the area; it does not experience other
forms of disturbance, including grazing, to any great degree; and although non-native vegetation
and a high cover of graminoids are present, plants persist.
3
All of the other sites visited are associated with smaller streams or seasonal ponds that likely do
not experience the water flow events and seasonal inundation needed to maintain habitat.
Southern Oregon has also been experiencing drought from 2012 through 2014. While this may
be the main factor in decline of Rorippa columbiae at these sites, plants also contend with other
factors such as grazing, OHV use and/or noxious weed infestation. Grazing impacts were noted
to cause substantial ground disturbance at several sites. OHV use was mentioned as causing
minor impacts to the soil. Noxious weeds were often present, but not indicated as impacting
Rorippa columbiae populations at this point in time. But in combination with lower seasonal
water flows at these sites, these other factors could be having a fairly large impact. Although we
have no control over seasonal water flow, the other factors potentially affecting sites could be
mitigated.
Comments recorded at some sites: plants appear to be in remnant patches of what was a
continuous population 20 years ago, and plants are no longer present along intermittent stream
downstream of the reservoir, offer a fair summation of the trend observed.
Fig. 1 Sprague River Rorippa columbiae site
Status of other Final Products:
1) NRM/NRIS TESP survey and site forms and data entry – complete.
2) Share report with SO, RO, Lakeview BLM and compile additional information.
3) Determine next steps: another year of survey, survey of additional areas, etc.
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